Compound insulating-layer for electric coils



(No Model.)

B. THOMSON. COMPOUND INSULATING LAYER FOR ELEGTRIO GOILS.

Patented Mar. 4, 1890.

n, PETERS. PMGLGMW, Washington, u: c.

UNITED STATES PATENT -OF IcE.

ELIHU THOMSON, OF LYNN, MASSACHUSETTS.

COMPOUND INSULATING-LAYER FOR ELECTRIC COlLS.

SPECIFICATION forming part of Letters Patent No. 422,550, dated March 4,1890. A uanai filed August5,1ii89. steam. siaszs. (No model.)

To all whom it may concern;

Be it known that I, ELIHU THOMSON, acitizen of the United States, and aresidentof Lynn, in the county of Essex and State of Massachusetts, haveinvented a certain new and useful Compound Insulating-Layer for ElectricCoils, of which the following is a specification.

My invention relates to the construction of an insulating septum orlayer interposed between electric coils and their core or carrier, orbetween two sets of electric coils, for the purposeof maintainingthorough insulation between the parts lying at opposite sides of suchlayer.

My invention is particularly applicable to the case of armatures fordynainogenerators and motors having a laminated iron core of cylindricalform, upon which is first wound a layer or layers constituting one halfthe winding, connected, as is well known, to one half the segments ofthe commutator, superposed on which winding and altogether outsidetherof the other half of the winding is placed and connected to theother half of the commutator-segments. The winding then consists of twosets of superposed coils at right angles or approximate right anglesplaced on the core, the wires of one set underlying those of the otherset.

The object of the invention, as thus applied, is to secure asatisfactory insulation between the wires of the two sets or two layersor sets of layers just referred to and at the same time secure a mosteffective insulation on the under side of the inner wire from thearmature-core itself.

My invention consists, essentially, of a compound insulating layer orseptum composed of two or more parts, one of which is nonporous or ofclose texture or nature-+such as mica, glass, or similar earthy ormineral substance-and impervious to moisture, while the other part,forming a bolster or backing to which the first is bound, consists ofsome fibrous or non-lamin ated material, preferably in the form of clothwoven or felted, and composed, preferably, of non-inflammable ma terial,like asbestus.

My invention consists, further, in certain additional features used inconnection with the above, as will be hereinafter described.

erable to employ it.

In the accompanying drawings, Figure 1 is a cross section through apartof an armature, showing my invention as applied thereto.

Fig. 2 is a longitudinal section through one end of the armature,showing the location of the compound insulating-layers.

O is the armature-shaft; B, the plates or laminee of iron forming, inconnection with the head A, a portion of the core or carrier to whichthe armaturecoils are applied.

D indicates the wires of the inner set of windings, and D those of theouter set. These wires are provided with the usual attachedinsulating-sheath, as indicated.

In constructing the armature with my invention applied I proceed asfollows: On the core I first place the fibrous coating to, which ispreferably of non-inflammable material, such as asbestus paper or cloth.This layer of my compound insulation may be bound down upon its core orsupport by a covering b, of cotton or other cloth, or by other means, asdesired. The cloth is preferably shellacked.

If the fibrous coating or layer of asbestus or other material be strongenough in itself to withstand handling and working, the binding or layerof cotton or other cloth may be dispensed with. In practice, however, itis pref- Next is applied the layer of insulating material (non-porous)formed of some vitreous or earthy material, such as mica in the formofthin plates. One or two layers of mica 0 maybe applied, according to itsthickness. The joints of the plates or laminae are overlapped, so as toform a complete layer impervious and nonporous. This layer may be bounddown by any suitable means and the coils of the armature wound directlyupon it; but in order to prevent injury to the upper vitreousornon-porous layer I prefer to cover it with a protective layer (1, ofsome material, such as cotton or linen cloth shellacked, or, betterstill, with one or two layers of hard, close, and strong paper, which isshellacked down in place. The work of winding the coils may be then donewithout risk of displacing the under layers.

As will be seen, by this procedure there has been produced a compoundlayer of insulating material consisting of the combination of fibrousmaterial-sueh as asbestusfire-resisting and heat-resisting in character,

and vitreous or mineral material in laminae or plates, altogetherimpervious to the passage of vapors, and representing a thin sheet ofglass, as it were, surrounding the core.

The mechanical attrition or vibration would be apt to disturb the micaif it were alone, while it would be difficult, if not impossible, to putit on the core. The asbestus, being fibrous or flexible in itscharacter,thoroughly makes up for any deficiency in the mica coating, atleast so far as a heat-resisting layer is concerned. If desired, anextra layer 0 of mica may be applied over those already referred to, anda protective layer 6 applied over 0 The ends of the core are insulatedwith card-board or asbestus plates, over which is placed acompound micaand linen plate or washer, or mica and paper might be used. The nextstep in the construction is the laying on of the first half of thesystem of coils, which constitutes the inner winding. This windingcompletely incloses the armature-core, and presents outwardly a surfaceof insulated wire, over which there is to be placed the other halfwinding.

Since the potential between the respective portions of this winding mayat times be high, as my lllVBlltlOll is particularly applicable torailway-motor work using potentials of four hundred, five hundred, orsix hundred volts, I coat the first set of wire coils all over with amica layer re-enforced on each side, or on one side only, with cottoncloth, linen,or paper, so as to combine again an impervious, vitreous,or mineral layer with a fibrous perviousinsulating-layer. This isindicated in Fig. 1. The thickness of the insulation between the twosets of windings, outer and inner, is, however, not as great as thatbetween the inner winding and the core itself. The shaft, where the wireof either winding comes near, is in like manner insulated, or two layersof stout twine may be wound around it and the whole be well shellacked.Between the two sets of windings on the ends are placed the sameinsulating material, so as to substantially divide the insulating-wireinto two coil-sections, an inner and an outer, although the whole of thetwo sets consecutively follow in the ordinary plan of the Siemenswindings, or consecutive coils angularly follow each other around thecircumference of the armature.

The wire in each coil-section may be one, two, or more layers deep,according to the number of turns required to exist in a given space.

What I claim as my invention is- 1. The combination,with electric coilsand the core or support upon which they are wound, of an interposedcompound layer of insulating material comprising a layer or base of afibrous insulating material, and an external layer of a hard non-porousmaterial fastened upon the first, as and for the purpose described.

2. The combination, with electric coils and their core or support, ofinterposed layers of insulating material comprising a sheet or layer ofan insulating mineral substance in a form impervious to moisture appliedover a layer of a non-inflammable fibrous substance.

3. The combination, with electric coils and the base or support overwhich they are wound, of an interposed compound layer of insulatingmaterial consisting, essentially, of a base of asbestus paper or cloth,a superposed layer of mica, and an external covering of insulatingmaterial applied over the mica, as and for the purpose described.

4. The combination, with two sets of windings of conducting-wire havingan attached insulating-sheath and applied to an armature core or body,of an interposed compound layer of insulating material consisting of asheet or sheets of mica and a sheet or sheets of a fibrous insulatingmaterial.

5. A compound layer of insulating material consisting of a base ofasbestus, a pro tective and fastening cover of a stronger material, asuperposed layer of mica, and an external protective insulating-coverover the mica.

Signed at Lynn, in the county of Essex and State ofhiassachusetta'this1st day of August, A. D. 1889.

ELIHU THOMSON.

Witnesses:

JOHN W. Gmnonnr, A. L. ROHRER.

